Concrete blocks for free standing and retaining walls have been known and used for many years. They can be both functional and decorative, and range from small gardening applications to large-scale construction projects. Such walls are typically used to form horizontal surfaces or terraces by providing a generally vertical barrier behind which backfill may be deposited. Such walls reduce erosion and slumping and maximize land use.
Walls can be constructed from stackable concrete blocks. Blocks are stacked in horizontal rows called courses. Multiple successive courses may be used to create a vertically rising wall of a desired height. These types of blocks can generally be assembled quickly and economically due to the interlocking of adjacent courses of blocks. Typically, each block includes some type of interlocking system such as pins, lips or projections so that one course of blocks interlocks with an adjacent course of blocks to create a stable structure. These features are often located on the bottom surfaces of the blocks and project downward into an opening in a lower course of blocks because if the projections are on the top surface of the blocks the wall will require specially manufactured cap blocks. This, however, can cause problems with the first course of blocks because it is laid directly upon the base surface so there is no open area for the interlocking features to rest in. In order to create a level base course, builders often have to excavate material from the base surface. This process often makes the base course the most difficult and time consuming course to build. Alternatively, blocks manufactured without projections can be used in the base course. This, however, requires having two different types of blocks on hand which increases the cost and complexity of stacking, manufacturing, storing, and palletizing the blocks.